In ships, propulsion systems generate a propulsive force for navigation. One of the propulsion systems is a variable pitch propeller having numerous blades each having a variable pitch in consideration of navigation conditions of the ship.
However, such a variable pitch propeller is designed such that all of the numerous blades are changed in pitch at the same angle, and does not easily maximize propulsion efficiency.
In other words, a speed at which a fluid is introduced toward the variable pitch propeller located at the stern of the ship is not uniform. Nevertheless, a pitch set based on an average fluid speed is equally applied in all the variable pitch propellers. Thus, a region in which the blade pitch is greater in comparison with the speed at which the fluid is introduced undergoes a cavitation phenomenon, which is mainly responsible for hull vibrations and rudder wear.